Soft actuators (SAs) have been used in many compliant robotic structure and wearable devices, due to their safe interaction with the wearers. Despite advances, the capability of current SAs is limited by scalability, high hysteresis, and slow responses. In this paper, a new class of soft, scalable, and high-aspect ratio fiber-reinforced hydraulic SAs is introduced. The new SA uses a simple fabrication process of insertion where a hollow elastic rubber tube is directly inserted into a constrained hollow coil, eliminating the need for the manual wrapping of an inextensible fiber around a long elastic structure. To provide high adaptation to the user skin for wearable applications, the new SAs are integrated into flexible fabrics to form a wearable fabric sleeve. To monitor the SA elongation, a soft liquid metal-based fabric piezoresistive sensor is also developed. To capture the nonlinear hysteresis of the SA, a novel asymmetric hysteresis model which only requires five model parameters in its structure is developed and experimentally validated. The new SAs-driven wearable robotic sleeve is scalable, highly flexible, and lightweight. It can also produce a large amount of force of around 23 N per muscle at around 30% elongation, to provide useful assistance to the human upper limbs. Experimental results show that the soft fabric sleeve can augment a user’s performance when working against a load, evidenced by a significant reduction on the muscular effort, as monitored by electromyogram (EMG) signals. The performance of the developed SAs, soft fabric sleeve, soft liquid metal fabric sensor, and nonlinear hysteresis model reveal that they can effectively modulate the level of assistance for the wearer. The new technologies obtained from this work can be potentially implemented in emerging assistive applications, such as rehabilitation, defense, and industry.

Minimally invasive surgery (MIS) has evolved as an effective method for cardiovascular diseases (CVDs) and gastrointestinal (GI) cancers. Recently, soft robotic catheters using soft materials have attracted considerable attention thanks to their ability to navigate through intricate anatomical structures and perform precisely controlled movements. However, current systems are powered by rigid pull-wire mechanism, showing substantial nonlinear hysteresis and high force loss. Furthermore, they require several actuators to manipulate the bending tip for working in the intricate anatomical corners of the internal organs. For thrombus removal, the approach of stent retrieval via a catheter has various drawbacks including difficult manipulation, insufficient retrieval force, and complexity. Herein, new soft robotic catheters are introduced to address these challenges. The new catheters can achieve bidirectional bending motion and spiral shapes using a single soft actuation source. They are equipped with a portable and ergonomic control interface. Mathematical models for the bending effector are developed and experimentally validated. The new soft robotic catheters potentially allow for quicker and more accurate manipulation to reach any target inside the cardiac and GI regions, enabling faster and more targeted ablation and thrombus removal therapy to enhance patient outcomes.

The heart’s intricate myocardial architecture has been called the Gordian knot of anatomy, an impossible tangle of intricate muscle fibers. This complexity dictates equally complex cardiac motions that are difficult to mimic in physical systems. If these motions could be generated by a robotic system, then cardiac device testing, cardiovascular disease studies, and surgical procedure training could reduce their reliance on animal models, saving time, costs, and lives. This work introduces a bioinspired soft robotic left ventricle simulator capable of reproducing the minutiae of cardiac motion while providing physiological pressures. This device uses thin-filament artificial muscles to mimic the multilayered myocardial architecture. To demonstrate the device’s ability to follow the cardiac motions observed in the literature, we used canine myocardial strain data as input signals that were subsequently applied to each artificial myocardial layer. The device’s ability to reproduce physiological volume and pressure under healthy and heart failure conditions, as well as effective simulation of a cardiac support device, were experimentally demonstrated in a left-sided mock circulation loop. This work also has the potential to deliver faithful simulated cardiac motion for preclinical device and surgical procedure testing, with the potential to simulate patient-specific myocardial architecture and motion.

Palpation is a simple but effective method to distinguish tumors from healthy tissues. The development of miniaturized tactile sensors embedded on endoscopic or robotic devices is key to achieving precise palpation diagnosis and subsequent timely treatment. This paper reports on the fabrication and characterization of a novel tactile sensor with mechanical flexibility and optical transparency that can be easily mounted on soft surgical endoscopes and robotics. By utilizing the pneumatic sensing mechanism, the sensor offers a high sensitivity of 1.25 mbar and negligible hysteresis, enabling the detection of phantom tissues with different stiffnesses ranging from 0 to 2.5 MPa. Our configuration, combining pneumatic sensing and hydraulic actuating, also eliminates electrical wiring from the functional elements located at the robot end-effector, thereby enhancing the system safety. The optical transparency path in the sensors together with its mechanical sensing capability open interesting possibilities in the early detection of solid tumor as well as in the development of all-in-one soft surgical robots that can perform visual/mechanical feedback and optical therapy.

Work-related musculoskeletal disorders (WMSDs) are often caused by repetitive lifting, making them a significant concern in occupational health. Although wearable assist devices have become the norm for mitigating the risk of back pain, most spinal assist devices still possess a partially rigid structure that impacts the user’s comfort and flexibility. This paper addresses this issue by presenting a smart textile-actuated spine assistance robotic exosuit (SARE), which can conform to the back seamlessly without impeding the user’s movement and is incredibly lightweight. To detect strain on the spine and to control the smart textile automatically, a soft knitting sensor that utilizes fluid pressure as a sensing element is used. Based on the soft knitting hydraulic sensor, the robotic exosuit can also feature the ability of monitoring and rectifying human posture. The SARE is validated experimentally with human subjects (N = 4). Through wearing the SARE in stoop lifting, the peak electromyography (EMG) signals of the lumbar erector spinae are reduced by 22.8% ± 12 for lifting 5 kg weights and 27.1% ± 14 in empty-handed conditions. Moreover, the integrated EMG decreased by 34.7% ± 11.8 for lifting 5 kg weights and 36% ± 13.3 in empty-handed conditions. In summary, the artificial muscle wearable device represents an anatomical solution to reduce the risk of muscle strain, metabolic energy cost and back pain associated with repetitive lifting tasks.

Flexible and wearable devices employing acoustic sensors have emerged as promising alternatives for continuous monitoring of physiological mechano-acoustic signals during daily activities, offering distinct advantages over conventional rigid stethoscopes. However, the limited low-frequency sensitivity of commercial MEMS acoustic sensors constrains their ability to accurately capture vital physiological signals. Here, we present a wireless, flexible auscultation patch (AusculPatch) that overcomes these limitations by employing a highly sensitive cantilever pressure transducer (CPT). The combination of a narrow airgap in CPT together with the ultra-low mass of the nanothin cantilever enables precise measurement across a broad acoustic frequency range (0.2 Hz to over 10 kHz), allowing the detection of multiple physiological mechano-acoustic signals, including pulse waves, Korotkoff sounds, cardiac signals, respiration patterns, and vocalizations. The single-chip architecture simplifies circuitry, enabling a lightweight design ( ~ 3.2 g), compact form factor (20×47×3.5 mm), and low power consumption (4.5 mW), making AusculPatch an ideal platform for continuous wear for cardiorespiratory monitoring and potentially sleep quality assessment. These features represent a significant advance in the development of low-cost and multifunctional wearable devices capable of multi-site auscultation for home-based wellness monitoring as well as Artificial Intelligence (AI)-assisted diagnosis and Human-Machine Interaction (HMI) applications.